Resonators and filters are known which comprise a dielectric, the permittivity of which is adjustable for adjusting the resonance frequency in the resonator. Thereby, an electric control field is used for adjusting, which electric control field is generated by means of an electrode structure which is applied to an LTCC (Low temperature cofired ceramic) over resistor layers. The LTCC and, thus, the electrode structures are affixed or installed at surrounding walls or limiting walls of the cavity resonator.